The present invention relates to meters for measuring usage of electricity in residential and commercial buildings. Such meters are typically referred to as "electricity meters" or "watt hour meters" and generally include an electric motor in which speed is related to power used in the building. The motor includes an armature having a disk that is partially visible through the meter's clear dome and that rotates at a speed proportional to instantaneous energy. The disk, in turn, drives gears of a numerical meter having dials that integrate instantaneous energy over time to indicate power, generally in watt hours. The difference between readings of the numerical meter at different times indicates electric power consumption during the intervening period.
Conventional electricity meters are read manually and, therefore, require that the electric utility send a field operator to periodically check every meter in the area it serves.